A day after Theresa May delivered the 'Article 50 letter' to Donald Tusk, the Government published proposed legislation to transfer legal powers back to the UK after Brexit.
Ministers have a huge task on their hands - preventing chaos and legal "black holes" as the country is pulled out of the European Union.
In order to tackle this challenge, the Government is proposing a complex and large-scale legislative project - The Great Repeal Bill.
What is the Great Repeal Bill?
In simple terms the bill is legislation, proposed by the Government, which would set into motion the transfer of all EU laws into UK laws on the day of Brexit.
In doing so, it will repeal the European Communities Act 1972 – which is the legislation underpinning Britain’s membership of the EU.
As explained in the Prime Minister’s foreword in the ‘Legislating for the United Kingdom’s Withdrawal from the European Union’ White Paper, the Bill will ensure that “the same rules and laws will apply on the day after exit as on the day before”.
And, then if any changes were to be made to primary legislation it would have to go through the processes of Parliament – debate and scrutiny.
Why is it needed?
EU laws and regulation form a huge part of UK legislation.
As a result, leaving the EU with no legislative provision would leave the legal system with huge gaps.
In order to “deliver a smooth and orderly Brexit” the Bill will transfer existing EU law into domestic law, after which Parliament will be able to decide which elements of that law to keep, amend or repeal.
Brexit Secretary David Davis has stressed that the Bill is “not a vehicle for policy changes”.
He wrote in the White Paper: “It will give the Government the necessary power to correct or remove the laws that would otherwise not function properly once we have left the EU.”
Why is it controversial?
Aside from the obvious controversy surrounding Brexit, the Bill has sparked concern over the use of so-called ‘Henry VIII powers’.
These powers allow the Government to pass up to 1,000 pieces of secondary legislation without the usual close parliamentary scrutiny employed when passing primary legalisation.
But Mr Davis said any powers created in this way would be "time limited" and "Parliament will need to be satisfied that the procedures are appropriate".
He said the Bill will provide a power to "correct the statute book where necessary" using secondary legislation - which some critics have warned will not allow full parliamentary scrutiny of the process.
“This power will be time limited and Parliament will need to be satisfied that the procedures in the Bill for making and approving the secondary legislation are appropriate,” he said.
He added that there was a "balance to be struck between the importance of scrutiny and correcting the statute book in time.”
Another contentious area is the role of the European Court of Justice (ECJ).
Mr Davis said the Bill will not give the ECJ a "future role" in the interpretation of UK laws, and courts will not be obliged to consider cases decided by the ECJ after Brexit.
ECJ case law would be given the same status as Supreme Court decisions, which can be overruled by subsequent rulings in the UK's highest court.
What will it actually do?
The three key steps are:
1. Repealing the European Communities Act and thus returning all power to UK institutions
2. Converting EU law as it stands at the moment of exit into UK law before exiting the EU. This will allow businesses to continue operating knowing the rules have not changed significantly overnight, and provides fairness to individuals, whose rights and obligations will not be subject to sudden change.
3. Creating powers to make secondary legislation. This will allow ministers to make amends to laws that would not function appropriately once we have left the EU.
It will also enable domestic law to reflect the content of any withdrawal agreement under Article 50.
Mr Davis told the House of Commons that the Bill will provide "clarity and certainty" for businesses and citizens as Brexit takes place.
"We have been clear that we want a smooth and orderly exit, and the Great Repeal Bill is integral to that approach.
"It will provide clarity and certainty for businesses, workers and consumers across the United Kingdom on the day we leave the EU.
"But it will also ensure that we deliver on our promise to end the supremacy of EU law in the UK as we exit,” he said.
In a foreword to the paper, Prime Minister Theresa May said the bill would "provide maximum certainty as we leave the EU".
"The Great Repeal Bill is an important part of our plan to deliver a smooth and orderly Brexit that commands the confidence of all," she added.
Although the White Paper did not specify a precise figure for the number of EU rules which will be transferred into domestic law, it noted that there are currently more than 12,000 EU regulations in force.
It also noted that Parliament has passed 7,900 statutory instruments implementing EU legislation and 186 Acts which incorporate a degree of EU influence.
When will it come into effect?
The Bill will be proposed at the start of the next Parliamentary session and will come into effect on the day of Brexit.
What have people been saying about it?
Campaigner Gina Miller, who successfully took the Government to court over its plans to trigger Brexit without parliamentary approval, has already said she was considering legal action to challenge the use of Henry VIII powers to alter individuals' rights.
Speaking to Emma Barnett on BBC Radio 5 Live Daily, she said: "The Government has already blotted its copybook by trying to bypass Parliament and use the Royal Prerogative, so if there is any sniff that they are trying to use Henry VIII powers, that would be profoundly unparliamentary and democratic."
Labour MP Chuka Umunna, chairman of Vote Leave Watch, described the Great Repeal Bill as "an immense undertaking, fraught with danger".
And Liberal Democrat chief whip Tom Brake described it as a “shameless power grab under the cloak of secondary legislation would have made Henry VIII blush”.
But the director-general of the British Chambers of Commerce, Adam Marshall, said the “certainty, stability and continuity” of the Bill would be “welcome” top UK businesses.
And CBI deputy director general Josh Hardie said businesses would welcome the Government's drive of clarity and certainty.